I don't own Honkai Impact and Seraph of the End

In the Underground vampire city of Sanguinem a line of children stood in line in the blood donation center for the vampiric overlords and as they entered the building they were hooked up to the Blood Extraction machine, sucking from their bodies, and once they had donated the required amount, they were unhooked and left to go but before they left the building they were given protein packs so they didn't die from the lack of blood.

Then scene then changes to three children resting in the sidewalk, one was boy and the other was a girl about 12 years of age, he had blue eyes and wavy blond hair, and the girl in front of him had Black hair.

Both were wearing the same attire which consisted of: sleeveless Hoodies, short pants, and sneakers.

"Dow we really HAVE to take these Protein packs?!" Yuu Complained as she pulled the half finished pack away

"Just finish the pack Yu, it's not going to kill you." Mika told her as he finished his protein pack

"I wished I didn't feel so weak." Yuu thought to herself as she walked towards the pathway's stone railing, and hated the feeling of hopelessness as she and every kid were being held at the mercy of the bloodsuckers.

"I could give you the power you so desire." Came a voice from the confines of her mind.

"What?!" Yuu suddenly exclaimed

"You said something Yuu?" Mika asked her, wondering what made her to exclaimed.

"Nothing Mika, thought I heard something." Yuu said as she finished her protein pack.

"As you say Yu, besides cheer up Akane might be making curry." Mika said as he smiled at her.

After they finished their little conversation Yuchiro throws her pack to the trash bin, then walks of to the house where she, Mika and the other kids from the Hyakuya orphanage lived, then she stopped when she saw a vampire stepping on a kid's while his buddy kicked the other kid next to him.

"Watch where you stay Livestock." Said a Vampire with a mocking as he crushed the Boy's hand with his shoe, causing the kid to cry in pain.
However Yuu being a hot head walked up to the two vampires.

"HEY! Apologize to those two." Yuu told them causing them to stop.

Then both Grunts turn around to see Yuichiro as if she were just a measly insect not worth the attention, and both of them though who was this girl demanding to apologize to what was essentially Livestock to them.

"Did you say something Livestock?" Said the Vampire to the right as he walked towards Yuu

As Yuu was about to answer she was stopped by Mika.

"Please forgive my friend, she stepped out of line." Mika told them but they didn't listen the Vampire walked towards them and grabbed Yuu by the shirt's neck, and took her over to the Ledge.

"Now what do you think you are doing gents?" Came a male voice.

The the grunt holding Yu threw her back to the street not wanting to enrage the 7th progenitor.

"Lord Bathory forgive us, is just that this livestock stepped out of line." The Vampire said as he bowed before Ferid who had an amused smile on his face.

"By throwing her from the ledge, come now that won't do, anyway what's done is done off you go." Ferid said as he dismissed the vampires who simply nodded their heads.

"Have a good day Lord Bathory." The Vampires said as they began to leave.

"Hello Mika-Kun." Greeted Ferid with happy tone.

"Thank you for your help lord lord Bathory." Mika said as he bowed before Ferid

"You and your little friend are more then welcomed Mika." Ferid said as the kids walked pass him

"By the way same time as always?" Ferid asked Mika, which caused the two to stop for a moment.

"Yes same time as always." Mika said with a nod.

Then Ferid went up and left, same did Yu and Mika while the Latter left for the house where they lived with the other Children from the orphanage.

While both Mika and Yuu left for the house where she, Mika and the other orphans lived, but Yuu couldn't help but ponder what Ferid and Mika meant earlier, so she decided to ask Mika.

"Mika, what what were you and Bathory talking about earlier?" Yuu asked Mika which caused the boy to freeze in his tracks for a moment not knowing what to answer.

"It's just mutual understanding Yuu." Mika dodged the question

But Yuichiro wasn't buying it.

"Why are you defending that bloodsucker Mika?" Yuu asked Mika wondering what Ferid to cause Mika to trust him.

"I will tell you later Yuu." Mika said.

As the two children went for their house the scene changes into white where latter it reveals a woman in her mid twenties Black hair as the darkest night, emerald green eyes which were silted like a cat, and was sporting a purple trench coat with the left sleeve being torn of, thigh high boots, a sleeveless white shirt and the left arm looked as it had a grid like tattoo and was in a purple color, she was sitting in throne like chair while drinking some wine.

"This is a very interesting host, I wonder what would cause her to go over the edge. All in good time, all in good time." The Woman said as she started chuckling, and the chuckle turned into a cruel laughter, at the thought of cleaning up the mess that is humanity and the vampires, and wipe the slate clean.

And as she laughed like a madwoman no one noticed the feint electric green glow on Yuichiro's back.

Later

As Yuichiro and Mika arrived at the house where both and the other Hyakuya orphans lived, Yuichiro knocked the door and a girl a year younger then Mika and Yuichiro opened the door, she had dark brown colored hair and light brown eyes, she wore a dark choker with a tag and a sleeveless one piece dress with a hood, this was Akane Hyakuya who was often called Mika's second-in-command by Yuichiro.

"Hey Akane what's up!" Yuu greeted Akane

"Hey guys." The girl greeted them.

"Hey Akane, what are you doing?" Mika asked Akane

"I'm doing Fine guys, and come on in guys I just made Curry." Akane said as she made way inside

The both of them enter the house, where the other orphans live.

Small timeskip (as I am lazy to write her interaction with the other kids and you probably may have watched the anime, read the manga or LN version)

As was all were asleep, Yuichiro couldn't help but think about Mika safety after he left for Ferid's was he in danger, what would that Ferid do to him, she was concerned about him.

Then as she was about to fall asleep, Mika popped from to her bed waking her up.

" Mika, what the hell!?" Yuu complained as she looked at Mika

"Common Yu, there few things I want to talk with you in the Kitchen." Mika said.

"Fine." Said Yuu as she got off from her bed she went downstairs to the kitchen where Mika had put a cup filled with curry.

"Sit down." Said Mika as he pointed at the table in front of them.

As Yuichciro sat down and started eating the curry in front of her same with Mikaela.

"So what's all this about?" Yuu asked Mika

"We are getting out of here." Mika said which caused Yuichiro to stop eating for a moment and look at Mika.

She then dropped her spoon in the cup.

"have you lost your mind or something Mika!? And Besides how are we exactly going to get out of here, it's not as if the Vamps made it easier to walk out of here." Yuu said as she berated Mika

"I'm being serious about it Yu, here look." Mika said as he pulled a piece of paper which it was revealed to be a map of the city.

"Where did you get this Mika?" Yuu asked Mika wondering where he got it from.

"I got it from Ferid's mansion it's a map of the city down the smallest detail." Mika said causing Yuu to look at it with a tinge of hope, yet she was weary that this may have been a trap.

"Mika please tell me that you are sure is not a trap?" Yuu asked Mika.

"I'm sure, besides even if it's a trap I also got this." Mika said as he then pulled out a pistol which he also got from Ferid, this go Yuu to feel something wrong in her gut and thought that this was way to convenient.

"Yuu calm down, and besides we are finally getting out of here, just as you always wanted." Mika told Yuu.

"Fine." Yuu relented.

" Then it's settled go wake up the kid's and tell the we are leaving." Mika told Yuu to which she nodded.

"Ok." Yuu said as she went back to the bedroom to wake up the other kids, and told them to wake up as they would leave the city and go to the outside world.

Timeskip (Brought to you by Chibi Yuu Zapping Chibi Ferid to death.)

As Yuchiro, Mika, Akane and the other kids stood in front of the exit but before the could go any further they heard some clapping, and from the shadows Ferid showed up.

"What the hell is going on?" Yuu asked as she was surprised by the sudden appearance of Ferid.

"Mika-kun~ I knew I would find here, and what's you brought you brought some little lambs along with you?" Ferid said in a singsong tone.

Then Mika took a look on the map in hands, but was blown off his hands.

"This was a trap all along!" Yuu thought to herself Knowing that they couldn't win against the noble, they had only one way to escape.

"RUN!"Yuu Yelled

And as soon as Yuu yelled those words everyone started to run, which she came to regret as soon as she saw Ferid killing them, Yuu couldn't move a single muscle she was to scared to eve move an inch, as this was happening Ferid killed every child that was running for the exit, as if it all was just a game, and killing Akane last, then he turned his attention to Yuichiro and charged at her.

But as Ferid made his way to kill her, he was stopped by Mika who shot the pistol in his hands.

Though Ferid dodged it in time.

"Mika, isn't that my gun? How naughty of you." Ferid said in a Cheeky tone as he charged at Mika

But as he was about to take a second shot, the arm which he was holding his gun was chopped off, dropping the gun.

And yet Yuichiro stood there doing nothing as every one around her was dead or in Mika's case dying.

"Do you wish for power?" Came a woman's voice.

"What?" Yuu asked

"Do you wish for power to avenge your family?" Asked the Voice

Yuichiro couldn't believe what she was hearing, she must be loosing her mind.

"Answer me girl do you want revenge or die for here for nothing?!" The Voice yelled at here.

Yuichiro didn't have much of a choice she would have to accept.

"Yes, I-I accept." Yuu accepted.

"Good now all you have to do is to let go." The Voice said

Yuichiro the did as the voice told her and let go, and so her world turned to dark.

With Ferid and Mika.

"Such shame Mika, I surely will miss the times you came by my house, your blood tasted like a fine wine and I'm sure will miss it, Though I am curious how will your sister's blood will taste like." Said Ferid removed his arm from Mika's chest he then charged at Yuu and the Blond couldn't do anything about but watch as he bled out.

"Yuu" Mika weakly called out her name, Ferid was close to killing Yuu, He the was launched backwards by a stream of lighting. Then Yuu got up on her feet and started walking towards Mika.

"Yuu?" Mika simply asked.

"Don't worry brat you friend is well under my care." She said in a cold tone devoid of any emotions, and didn't seem to care for her surroundings.

"Though I can't have you dying here." Said Yuu, when she bit her lip hard enough to draw blood, and kissed Mika, who felt as if some sort of power was surging through his body.*

"I will have to go, we will meet again soon enough, little Angel." Yuu said as she walked towards the Exit

"what happened to you Yuu?" Mika asked as he closed his eyes.

Timeskip

In the middle of a city that was nearby the entrance to Saguinem.

"That was quite the light show, kid." Came a male voice causing Yuu to turn behind and see face to face with a man who was dressed in a military uniform and was flanked by three women one had red hair and blue eyes and a blond man.

"Who are you, didn't the Virus kill the Adults?" Yuu asked them wondering where these guys.

"'Sup kid I'm Lieutenant Colonel Guren Ichinose of the Imperial Demon army, and we are going to use you to wipe out the Vampires. And as for your question, the Virus didn't really kill all humans and those that were lucky survived." Guren bluntly told Yuu.

"It doesn't matter what they do as long as I have my revenge." Yuu thought as she gave them her answer.

*1 Answer: I hade this Idea after reading the Story Praetorian of the Void some time ago.